Audi Expands European CNG Lineup

Volkswagen AG’s Audi unit is launching European variants of its A4 and A5 cars with engines capable of running on compressed-natural-gas fuel.

As with the A3 Sportback g-tron, the new A4 Avant g-tron wagon and A5 g-tron coupe are powered VW Group’s 2.0-liter turbocharged 4-cylinder engine modified to run on either gasoline or CNG. The engine makes 170 hp and 199 lb-f of torque.

Paired with a 7-speed dual-clutch automatic transmission, the new g-tron models have a CNG fuel efficiency rating of 3.8 liters per 100 km and generate 102 g/km of carbon dioxide emissions based on the European driving cycle. This compares with 5.5-liters/100 km and 126 g/km for the A4 g-tron under gasoline operation and 5.6 l/100 kg and 126 g/km for the A5 g-tron.

The CNG fuel is stored in tanks made from carbon and glass fiber-reinforced polymer. When the pressure drops below 10 bars, the system automatically switches to using gasoline.

In addition to standard CNG, the g-tron vehicles can use Audi’s own e-gas blend. The electrolysis “methanation” process used to make e-gas significantly lowers emissions compared with conventional CNG production techniques, according to the carmaker.

The A4 and A5 g-trons launched this summer in Europe. There are no plans to offer the vehicles in the U.S.